in plan9/mksyscall.go [94:387]
func main() {
// Get the OS and architecture (using GOARCH_TARGET if it exists)
goos := os.Getenv("GOOS")
goarch := os.Getenv("GOARCH_TARGET")
if goarch == "" {
goarch = os.Getenv("GOARCH")
}
// Check that we are using the Docker-based build system if we should
if goos == "linux" {
if os.Getenv("GOLANG_SYS_BUILD") != "docker" {
fmt.Fprintf(os.Stderr, "In the Docker-based build system, mksyscall should not be called directly.\n")
fmt.Fprintf(os.Stderr, "See README.md\n")
os.Exit(1)
}
}
flag.Usage = usage
flag.Parse()
if len(flag.Args()) <= 0 {
fmt.Fprintf(os.Stderr, "no files to parse provided\n")
usage()
}
endianness := ""
if *b32 {
endianness = "big-endian"
} else if *l32 {
endianness = "little-endian"
}
libc := false
if goos == "darwin" && strings.Contains(buildTags(), ",go1.12") {
libc = true
}
trampolines := map[string]bool{}
text := ""
for _, path := range flag.Args() {
file, err := os.Open(path)
if err != nil {
fmt.Fprintf(os.Stderr, err.Error())
os.Exit(1)
}
s := bufio.NewScanner(file)
for s.Scan() {
t := s.Text()
t = strings.TrimSpace(t)
t = regexp.MustCompile(`\s+`).ReplaceAllString(t, ` `)
nonblock := regexp.MustCompile(`^\/\/sysnb `).FindStringSubmatch(t)
if regexp.MustCompile(`^\/\/sys `).FindStringSubmatch(t) == nil && nonblock == nil {
continue
}
// Line must be of the form
// func Open(path string, mode int, perm int) (fd int, errno error)
// Split into name, in params, out params.
f := regexp.MustCompile(`^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*((?i)SYS_[A-Z0-9_]+))?$`).FindStringSubmatch(t)
if f == nil {
fmt.Fprintf(os.Stderr, "%s:%s\nmalformed //sys declaration\n", path, t)
os.Exit(1)
}
funct, inps, outps, sysname := f[2], f[3], f[4], f[5]
// Split argument lists on comma.
in := parseParamList(inps)
out := parseParamList(outps)
// Try in vain to keep people from editing this file.
// The theory is that they jump into the middle of the file
// without reading the header.
text += "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n"
// Go function header.
outDecl := ""
if len(out) > 0 {
outDecl = fmt.Sprintf(" (%s)", strings.Join(out, ", "))
}
text += fmt.Sprintf("func %s(%s)%s {\n", funct, strings.Join(in, ", "), outDecl)
// Check if err return available
errvar := ""
for _, param := range out {
p := parseParam(param)
if p.Type == "error" {
errvar = p.Name
break
}
}
// Prepare arguments to Syscall.
var args []string
n := 0
for _, param := range in {
p := parseParam(param)
if regexp.MustCompile(`^\*`).FindStringSubmatch(p.Type) != nil {
args = append(args, "uintptr(unsafe.Pointer("+p.Name+"))")
} else if p.Type == "string" && errvar != "" {
text += fmt.Sprintf("\tvar _p%d *byte\n", n)
text += fmt.Sprintf("\t_p%d, %s = BytePtrFromString(%s)\n", n, errvar, p.Name)
text += fmt.Sprintf("\tif %s != nil {\n\t\treturn\n\t}\n", errvar)
args = append(args, fmt.Sprintf("uintptr(unsafe.Pointer(_p%d))", n))
n++
} else if p.Type == "string" {
fmt.Fprintf(os.Stderr, path+":"+funct+" uses string arguments, but has no error return\n")
text += fmt.Sprintf("\tvar _p%d *byte\n", n)
text += fmt.Sprintf("\t_p%d, _ = BytePtrFromString(%s)\n", n, p.Name)
args = append(args, fmt.Sprintf("uintptr(unsafe.Pointer(_p%d))", n))
n++
} else if regexp.MustCompile(`^\[\](.*)`).FindStringSubmatch(p.Type) != nil {
// Convert slice into pointer, length.
// Have to be careful not to take address of &a[0] if len == 0:
// pass dummy pointer in that case.
// Used to pass nil, but some OSes or simulators reject write(fd, nil, 0).
text += fmt.Sprintf("\tvar _p%d unsafe.Pointer\n", n)
text += fmt.Sprintf("\tif len(%s) > 0 {\n\t\t_p%d = unsafe.Pointer(&%s[0])\n\t}", p.Name, n, p.Name)
text += fmt.Sprintf(" else {\n\t\t_p%d = unsafe.Pointer(&_zero)\n\t}\n", n)
args = append(args, fmt.Sprintf("uintptr(_p%d)", n), fmt.Sprintf("uintptr(len(%s))", p.Name))
n++
} else if p.Type == "int64" && (*openbsd || *netbsd) {
args = append(args, "0")
if endianness == "big-endian" {
args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name))
} else if endianness == "little-endian" {
args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name))
} else {
args = append(args, fmt.Sprintf("uintptr(%s)", p.Name))
}
} else if p.Type == "int64" && *dragonfly {
if regexp.MustCompile(`^(?i)extp(read|write)`).FindStringSubmatch(funct) == nil {
args = append(args, "0")
}
if endianness == "big-endian" {
args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name))
} else if endianness == "little-endian" {
args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name))
} else {
args = append(args, fmt.Sprintf("uintptr(%s)", p.Name))
}
} else if p.Type == "int64" && endianness != "" {
if len(args)%2 == 1 && *arm {
// arm abi specifies 64-bit argument uses
// (even, odd) pair
args = append(args, "0")
}
if endianness == "big-endian" {
args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name))
} else {
args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name))
}
} else {
args = append(args, fmt.Sprintf("uintptr(%s)", p.Name))
}
}
// Determine which form to use; pad args with zeros.
asm := "Syscall"
if nonblock != nil {
if errvar == "" && goos == "linux" {
asm = "RawSyscallNoError"
} else {
asm = "RawSyscall"
}
} else {
if errvar == "" && goos == "linux" {
asm = "SyscallNoError"
}
}
if len(args) <= 3 {
for len(args) < 3 {
args = append(args, "0")
}
} else if len(args) <= 6 {
asm += "6"
for len(args) < 6 {
args = append(args, "0")
}
} else if len(args) <= 9 {
asm += "9"
for len(args) < 9 {
args = append(args, "0")
}
} else {
fmt.Fprintf(os.Stderr, "%s:%s too many arguments to system call\n", path, funct)
}
// System call number.
if sysname == "" {
sysname = "SYS_" + funct
sysname = regexp.MustCompile(`([a-z])([A-Z])`).ReplaceAllString(sysname, `${1}_$2`)
sysname = strings.ToUpper(sysname)
}
var libcFn string
if libc {
asm = "syscall_" + strings.ToLower(asm[:1]) + asm[1:] // internal syscall call
sysname = strings.TrimPrefix(sysname, "SYS_") // remove SYS_
sysname = strings.ToLower(sysname) // lowercase
if sysname == "getdirentries64" {
// Special case - libSystem name and
// raw syscall name don't match.
sysname = "__getdirentries64"
}
libcFn = sysname
sysname = "funcPC(libc_" + sysname + "_trampoline)"
}
// Actual call.
arglist := strings.Join(args, ", ")
call := fmt.Sprintf("%s(%s, %s)", asm, sysname, arglist)
// Assign return values.
body := ""
ret := []string{"_", "_", "_"}
doErrno := false
for i := 0; i < len(out); i++ {
p := parseParam(out[i])
reg := ""
if p.Name == "err" && !*plan9 {
reg = "e1"
ret[2] = reg
doErrno = true
} else if p.Name == "err" && *plan9 {
ret[0] = "r0"
ret[2] = "e1"
break
} else {
reg = fmt.Sprintf("r%d", i)
ret[i] = reg
}
if p.Type == "bool" {
reg = fmt.Sprintf("%s != 0", reg)
}
if p.Type == "int64" && endianness != "" {
// 64-bit number in r1:r0 or r0:r1.
if i+2 > len(out) {
fmt.Fprintf(os.Stderr, "%s:%s not enough registers for int64 return\n", path, funct)
}
if endianness == "big-endian" {
reg = fmt.Sprintf("int64(r%d)<<32 | int64(r%d)", i, i+1)
} else {
reg = fmt.Sprintf("int64(r%d)<<32 | int64(r%d)", i+1, i)
}
ret[i] = fmt.Sprintf("r%d", i)
ret[i+1] = fmt.Sprintf("r%d", i+1)
}
if reg != "e1" || *plan9 {
body += fmt.Sprintf("\t%s = %s(%s)\n", p.Name, p.Type, reg)
}
}
if ret[0] == "_" && ret[1] == "_" && ret[2] == "_" {
text += fmt.Sprintf("\t%s\n", call)
} else {
if errvar == "" && goos == "linux" {
// raw syscall without error on Linux, see golang.org/issue/22924
text += fmt.Sprintf("\t%s, %s := %s\n", ret[0], ret[1], call)
} else {
text += fmt.Sprintf("\t%s, %s, %s := %s\n", ret[0], ret[1], ret[2], call)
}
}
text += body
if *plan9 && ret[2] == "e1" {
text += "\tif int32(r0) == -1 {\n"
text += "\t\terr = e1\n"
text += "\t}\n"
} else if doErrno {
text += "\tif e1 != 0 {\n"
text += "\t\terr = errnoErr(e1)\n"
text += "\t}\n"
}
text += "\treturn\n"
text += "}\n\n"
if libc && !trampolines[libcFn] {
// some system calls share a trampoline, like read and readlen.
trampolines[libcFn] = true
// Declare assembly trampoline.
text += fmt.Sprintf("func libc_%s_trampoline()\n", libcFn)
// Assembly trampoline calls the libc_* function, which this magic
// redirects to use the function from libSystem.
text += fmt.Sprintf("//go:linkname libc_%s libc_%s\n", libcFn, libcFn)
text += fmt.Sprintf("//go:cgo_import_dynamic libc_%s %s \"/usr/lib/libSystem.B.dylib\"\n", libcFn, libcFn)
text += "\n"
}
}
if err := s.Err(); err != nil {
fmt.Fprintf(os.Stderr, err.Error())
os.Exit(1)
}
file.Close()
}
fmt.Printf(srcTemplate, cmdLine(), goBuildTags(), plusBuildTags(), text)
}